Was just about to recommend this. Supporting Wordpress everyday, I find this is the best way to combat the problem. Another option would be to add an additional password for the directory. For you apache guys,
1. Disable PHP execution in the uploads directory (hmm, wonder if it'd work if I disabled it in the entire wp-content folder?).
2. Run PHP as a different user to the file owner.
Both of these are to minimise damage when an extension is exploited by a hacker (if it hasn't happened to you yet, it will do) and to reduce the damage done to the server/site.